Cloning is making a "copy" of the HDD onto another disk, such that that disk is and behaves just like the original.
You could "clone" your HDD C drive for example and put it onto a new or larger HDD and refit that it your PC. It would behave and boot etc just like the original.
Imaging is making a copy of the same HDD but the image file is of no use on it's own. It needs the software that made the image, to use to recreate the original image back on a HDD.
Imaging usually means "making a backup" which is a copy of thee HDD that you can restore from, and usually restoring that image back to where it came form if needs be.
The distinction isn't very obvious... imaging is kind of "the first step" in cloning a disk.
If you restore that image back... to do a system recovery you haven't "made a new disk", you have just put an "image" back on the same.
Cloning would give you as many disks as you wanted... all able to be swapped into your PC and used as if nothing had happened.